I have a 2012 cab and was wondering if the car has a front and rear brake wear sensor? Also, I read somewhere the rear pads can be replaced the first time without replacing the rotors. I have never heard this before. Is this true?

 

It should have a wear sensor. Maybe just one on one pad, but they seem like a std thing. Old school wear "sensor" was some sheet metal that stuck out and made contact with the disc, which made a terrible noise. The original wear sensor was when you hear the metal backing of the pad scraping the disc :o The only sensor I trust is physically looking at each pad. It not be very easy with yours but I often do it by feel, feeling for the gap between the pads backing and disc.
I'd imagine most will say to replace the discs, but my current car is the first time I've ever replaced the discs. I didn't need to, I just have more $ than energy now. The discs on my truck have well over 200k and are 47 years old. I replaced the pads once, around yr 2000. The discs needed turning by normal standards but I hit them with a sander and they're good to go. Same with any car I've had, front or back.
You just have to decide if you want to replace, turn, sand, or leave it as-is. Few places turn brakes these days, and few are redneck enough to sand them, so almost everyone replaces them. My guess is the cost of new are cheaper than turning.

You can try doing nothing but replace the pads, but in the past, from my experience, it was about 50/50 that it will squeal, which is why I sanded them. Since I don't hear brakes squeal anymore it makes me think the pads these days simply don't do that? When I was a kid there were a lot of cars squealing. I also used to treat the pads with a chemical to fix that, but it seems there's no need these days. I'd also bevel the pads but they come beveled now.
So if you don't want to buy new discs, and avoid the possible battle getting the old discs off, I wouldn't worry about it. Worst case is you don't like it and end up buying discs.
Of course this only applies if the discs look ok, because I've seen some gnarly "customer presents" youtube vids where the customer considers the brakes ok as long as the car still moves.

 

I also have a 2012 Cab and yes, the car has brake pad sensors. When it/they get too thin, you will get a message on the center console in red, "Check Brake Pad Wear". This just happened to me at ~61K miles. I had all four brakes and rotors replaced by my Indy for $800.